The Union Station rail corridor is the 6.4-kilometre hub of Toronto’s transit network and consists of a complex arrangement of approach tracks, passenger platforms, and four interlockings at Cherry, Scott, John, and Bathurst streets. The corridor supports GO Transit commuter trains, Canadian Pacific, Canadian National, VIA, and ON Rail operations. It has 14 station tracks with platform access and more than 180 signals, 250 switch machines, 40 kilometres of circuited track, and all associated infrastructure, dating back to the late 1920s. This will be replaced with state-of-the-art computer-based interlockings and LED signalling technology.

The scope of work has included track additions and upgrading, replacement of all special trackwork in the multi-track rail corridor extending four miles east and west of the station, and replacement of the 90-year old signaling system with new state-of-the-art signals, communications, power supply, CCTV, and SCADA systems.

This 10-20 year improvement program aims to relieve overcrowding and allow for future growth. A new storage yard for 10 commuter trains was constructed, and an existing train storage yard refurbished. A new platform with associated underground passenger circulation facilities has also been completed inside the station.